When I read "Bonus point" I thought of it as a currency of sorts to redeem for special items (Like the referral points)
Maybe instead of a free spin every month, you can save up bonus points which can later be used to redeem a retired Monthly Shop item? On your previous post you said "All retired items from Monthly Shops will eventually be able to be obtained rarely from Grandma Agnes later on." So I don't think anyone expects that the monthly shop items will later become impossible to obtain.
It gives a huge incentive to get a premium badge without becoming pay to win, or offering anything too big towards premium members, since non-members can still trade with premium members to receive the items. (Or trade earned potatoes towards receiving a premium badge!)
I'm still happy with Dappervolk, and I trust that you guys can change, adapt, and communicate with your player-base, thank you!